Money laundering is using the proceeds of ANY crime. And that includes tax offences.
So for example, if a club was paying players cash from the turnstiles to avoid paying PRSI and to help the player increase their net wages (by not paying personal tax), this itself is money laundering, as you are laundering the proceeds of a criminal act.
However, money laundering has been extremely difficult to prove, even in very serious cases involving drugs and the proceeds of serious crime. The Gardai generally focus on this very serious stuff and the small beer is let slip by.
The formation of the CAB is actually and admission of failure of money laundering legislation as it provides for the seizure of the proceeds of crime without the very heavy sentencing that a conviction for money laundering carries.